Extended Virulence Genotypes of<i>Escherichia coli</i>Strains from Patients with Urosepsis in Relation to Phylogeny and Host Compromise

TLDR

Among 75 urosepsis isolates of *Escherichia coli*, 29 virulence factor genes were detected by a novel PCR assay. The PCR assay achieved 100 % specificity and 97.1 % sensitivity, detected high prevalence of key virulence genes such as *fyuA*, *traT*, and a pathogenicity island marker across both compromised and non‑compromised hosts, and revealed distinct VF distributions among phylogenetic group B2 and other groups, underscoring its utility for molecular epidemiology of extraintestinal pathogenic *E.

Abstract

Among 75 urosepsis isolates of Escherichia coli, 29 virulence factor (VF) genes were detected by use of a novel polymerase chain reaction (PCR) assay. Compared with probe hybridization, the PCR assay's specificity was 100% and sensitivity 97.1%. fyuA (yersiniabactin: overall prevalence, 93%), traT (serum resistance, 68%), and a pathogenicity-associated island marker (71%) occurred in most strains from both compromised and noncompromised hosts. Present in <20% of strains each were sfaS, focG (F1C fimbriae), afaldra, bmaE (M fimbriae), gafD (G fimbriae), cnf1, edtB (cytolethal distending toxin), cvaC (colicin V), and ibeA (invasion of brain endothelium). Different VFs were variously confined to virulence-associated phylogenetic group B2 (as defined by multilocus enzyme electrophoresis); concentrated in group B2, but with spread beyond; or concentrated outside of group B2. These findings provide novel insights into the VFs of extraintestinal pathogenic E. coli and demonstrate the new PCR assay's utility for molecular epidemiological studies.